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Pat Dolan
October 5th 03, 12:35 AM
According to the HyperPhysics site, super novae are detectable out to
8 billion light years. And according to Hubell, super novae at that
distance should have a velocity relative to earth of 0.6c. This would
result in a relativistic time dilation factor of 1.25. Consequently,
the average of luminosity curves of super novae at 8 billion light
years should be stretched out by 25% as a result of relativistic time
dilation, when compared to closer super novae. Is there any data
demonstrating this?

Also, is there any detectable difference in doppler shifting of light
from the receding arms versus the advancing arms of galaxies at 8
billion light years distance? If so, is there any difference in the
mean rotational velocity of a large sample of galaxies at 8 billion
lys and above, versus, a large sample of 1 billion 2yrs and below?

Thanks,

Pat

Wolf Logan
October 6th 03, 10:31 PM
"Pat Dolan" > wrote in message
om...
> According to the HyperPhysics site, super novae are detectable out to
> 8 billion light years. And according to Hubell, super novae at that
> distance should have a velocity relative to earth of 0.6c. This would
> result in a relativistic time dilation factor of 1.25. Consequently,
> the average of luminosity curves of super novae at 8 billion light
> years should be stretched out by 25% as a result of relativistic time
> dilation, when compared to closer super novae. Is there any data
> demonstrating this?

I believe the light curve "stretching" is one of the factors used to help
determine distance to a galaxy -- one of the reasons why amateur observation
of extragalactic supernovae (and the subsequent establishment of said
supernovae's light curves) is so valuable these days.

> Also, is there any detectable difference in doppler shifting of light
> from the receding arms versus the advancing arms of galaxies at 8
> billion light years distance? If so, is there any difference in the
> mean rotational velocity of a large sample of galaxies at 8 billion
> lys and above, versus, a large sample of 1 billion 2yrs and below?

I'm not sure about rotational differences between galaxies at 8 billion ly
and those closer, but there is certainly a detectable doppler gradient
across rotating galaxies. this gradient can be used to determine the tilt of
the galaxy relative to our line-of-sight.

whether any of these effects can be detected directly by a single amateur
observer would depend on your equipment and your skill, I'd say.